I stupid friend of mine came over to feed my dogs when I was out. He watched my Plasme tv for a while and when he shut the system down he only turned the cable box off for opprox. 6 hours. I did have th Tv on pixal shift . Know my screen seams grainy in dark scenes . I does seem a little better after a rolling picture screen. How long do need to run the screen before it gets better?

You have dead pixels , It may cost more to fix than getting a new tv, ill recommend calling samsung and talking to them to see if your still under warranty. Thanks -JC 1-800-SAMSUNG (1-800-726-7864)Mon - Fri: 8am - Midnight (EST)Sat - Sun: 9am - 11pm (EST)

? 11:20
https://www.youtube.com/watch?v=5hVi5gd0aec
Oct 5, 2010 - Uploaded by z28r2fast4u
I checked two buffer boards and found 11 out of the 12 ic's bad.... my samsung, I post the video here, do you know how to test YMAIN and ZSUS ? .... Samsung PN50C450 with a bad Plasma Panel Shows how to replace the ...

it might sound strange but i think the screen has dropped. I have seen this happen before, is it just one line or 2 as the screen is fitted in the shield, its held by a thin rubber sometimes it can drop when the tv is being moved about or in a lot of vibration like moving it about in a car. now this may sound strange but the last time i fixed one i used 6 match sticks and clean them up and put them in the screen housing and it keep the screen in place after that. but beautiful when removing the screen case as you can inadvertently damage the screen, the screen is only a thick as a bit of cardboard. i suppose you could even put the tv upside down on the bed or something soft and wiggle the screen back into place. this would not damage thew tv and you will not have to take it apart.

Well I hate to be the party popper but...
It sounds like when you changed the parts that you damaged it. When you damage the TV it may appear as red,white,gray,blue,black, or sometimes orange (i think i haven't checked in a while. I would suggest taking it to a professional repair man. This can be pricey but it is my only suggestion at this point.
Best Regards!
-Jacob

The main power supply regulator section circuit fault. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Pull up older posts. http://electronicshelponline.blogspot.com/ It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.
Search the site by type in the "brand name" to your device; in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.

These blinks [flashes] are fault indication (Error Codes). From the number of blinks occur at one time switch ON, you can get an idea about the faulty circuit section inside it. This will make repair easy. These are called blinking codes. Make sure about the exact number of blinking of the standby/power LED, by switching On & OFF the set, for at least two times. Count it carefully. If you wish to get some details, check the site linked here. It has details about blinking codes, and fault locating procedure, to many popular brand TVs and other devices. http://electronicshelponline.blogspot.com/
If blinks continue without any pause, the main board is faulty.
Search the site by type in the "brand name" to your device, in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.

? 4:52
https://www.youtube.com/watch?v=k2QpYJp6MU8
Apr 12, 2014 - Uploaded by cr4zyw3ld3r
Hi my LG 47ln5700 tv set has thin greyish black horizontal lineson one side of the .... I hope this works good with Samsung LCD as well....

I have the same problem. No video just audio.No on screen display visible either (volume, channel labels) nothing.

Samsung tried to repair this under warranty TWICE within 2 months. Second time they replaced circuit board and it worked for another 8 months. So I paid $1.500 for a TV that died again after 1,5 year - this is ridiculous.

I have no idea what the reason might be and I wont try to fix this since samsung tech could not fix it without replacing circuit board.

SAMSUNG is known by the really famous CAPACITOR problems with Taiwan Capacitors that this condensers are not so good self-healing anymore in about a year of 3 or 4 and have leakage or are deformed. this can be several parts inside the chassis, when its get not the right capacity anymore but if its temperature goes up by time then there is coming up a forming of the capacity slowly back. 20 minutes aware this is the first part where you begin is the mains board of the hdtv
The use of Taiwan capacitors everywhere and too little stress tolerance 16 v where 13 v is used but its all
taken too tight , thats Samsung and many other Brands with Taiwanese capacitors token to tight about the volts .16v 10 v replace with 10 v higher models over the time the size of the capacitors are smaller than before.
replace with good German capacitors or a good Brand Japanese also in the mainsboard in the first place , and replace if there are all green colored 3 watt type resistors if they are used in the mains ACbord primary because the end-caps of this resistors if thats 3 watt type can have also sometimes problems because of shrink and distention because the heat and cold are playing parts by the Samsung resistors they are sometimes terrible of the green 3 watt type. use normal cheap Vishay resistors instead the have also no such problems for shure.

Yes.. check sound on all ch. with different inputs also. If no sound anywhere check wires going to speakers.. if they are good.. most likely you amp is bad.. most are built into the media board.. some are not.. check out shopjimmy.com

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.http://electronicshelponline.blogspot.com/
In some models of LCD TVS; the backlight inverter and its T'Con board will be a part of the panel itself, and will be a built-in type inside the LCD panel. If so, they can't be replaced. In this case; a panel replacement is the only repair. For some other models, the backlight inverter section circuit will be a part of the main power supply regulator [SMPS]. To such sets, the power supply section circuit too should trouble shoot. Contact any service technician. The circuit will differ with models and versions.

http://electronicshelponline.blogspot.com/
It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.